Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.
Kahoot! - Kahoot! makes it easy to create, play and share fun learning games in minutes—for any subject, in any language, on any device.
Brainscape - Find, create, and study SMART FLASHCARDS on any device. DOUBLE your learning speed using the most effective study system on the planet. Keep all your content in sync across Brainscape's website and your Android devices.
Sli.do - Slido is the ultimate Q&A and polling platform for live and virtual meetings and events. It offers interactive Q&A, live polls and insights about your audience.
Mentimeter - a web-based polling tool for workshops, conferences & events
Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.